Hydrocarbon conversion process



March 3l, 1959 J. H. RALEY E-rAL 2,880,249

HYDROCARBON CONVERSION PROCESS Filed Dec. 22, 1955 THEsR ATTORNEYHYDROCARBON CONVERSION PROCESS John H. Raley, Walnut Creek, Richard D.Mullineaux,

Oakland, and Seaver A. Ballard, Orinda, Calif., as-

signors to Shell Development Company, New York N.Y., a corporation ofDelaware Application December 22, 1955, Serial No. 554,733

9 Claims. (Cl. 260-668) This invention relates to an improved processfor the conversion of hydrocarbons including the breaking ofcarbon-to-hydrogen bonds under the influence of iodine. It relates moreparticularly to the conversion of hydrocar-` bons by reaction at anelevated temperature in the presence of iodine and an o-len.

It is a principal object of this invention to provide an improvedprocess for the conversion of hydrocarbons containing at least threecarbon atoms and containing nonaromatic carbon-to-hydrogenbonds todiierent hydrocarbons having a different carbon-to-carbon linkage and ahigher carbon-to-hydrogen ratio. Another object is to provide animproved process for the formation of one or more new or differentcarbon-to-carbon bonds between contiguous carbon atoms in a givenmolecule to produce an oleiinic, acetylenic, or aromatic bond. Speciiicobjects of the invention are to dehydrogenate aliphatic saturatedhydrocarbons to aliphatic olefins and diolens, alicyclic saturatedhydrocarbons to cyclic olens and aromatics, and alkyl aromatics havingside chains of two or more carbon atoms to the corresponding aromaticswith olenic side chains, and to dehydrocyclize aliphatic hydrocarbonsto, aromatics. These objects will be more fully understood and otherswill become apparent from the description of the invention.

Briefly, the present invention. is directed to a process for convertinghydrocarbons having at least three carbon atoms per molecule andcontaining non-aromatic carbonto-hydrogen bonds to diierent hydrocarbonshaving a diiferent carbon-to-carbon linkage and a highercarbonto-hydrogen ratio by contact with iodine at an elevatedtemperature in the presence of a hydrogen accepting olefin.

The invention will be described by reference to the accompanying drawingwherein the single figure thereof is a schematic representation of ainode of carrying out the process of the invention.

It has been found, as disclosed in copending U.S. application, SerialNo. 489,301 of l. H. Raley, led February 18, 1955, that new or differentcarbon-to-carbon linkages can be formed in an emcient manner bysubjecting a mixture of a hydrocarbon containing at least two carbonatoms and containing non-aromatic carbon-to-hydrogen bonds and areactive proportion of free iodine to an elevated temperature suicienttoeffect a C-to-H bondf cleavage in the molecule in the presenceof freeiodine. Heating of the compound at an elevated temperature in thepresence of free iodine effects C-to-H bond Vcleavage in the molecule,with the resultant formation of one or more new or different C-to-Clinkages to produce, inter alia, one. or more unsaturated linkages and/or a cyclic and/or a higher molecular weightV structure,

tive-v examples, the acyclic carbon atoms which lare iii-v and/or a newstructure having a different number of carbon atoms bonded directly to agiven carbon atom.

In the presence of iodine as reactant the breaking of a C-to-H bondnormally occurs with the reaction of an atom of iodine with the hydrogenatom to form a molecule of hydrogen iodide. To convert one aliphatic toa corresponding olenic bond in accordance with the abovedescribedprocess it is necessary to remove two hydrogen atoms, and two atoms ofiodine are therefore required. Similarly, to convert cyclohexane tobenzene, six hydrogen atoms must be removed and six atoms of iodine arerequired per molecule; and to convert normal hexane to benzene, eighthydrogen atoms must be removed and eight iodine atoms are required permolecule.

It has now been found that in the conversion of hydrocarbons having atleast three carbon atoms per molecule the amount-of iodine required tobe charged with thehydrocarbon to be converted can be substantiallyreduced by adding to the mixture of charge hydrocarbon and iodinespecies a substantial amount of a hydrogen accepting olefin. Said olenultimately is converted to a saturated hydrocarbon by addition of thehydrogen removed from the charge hydrocarbon while the latter isconvertedin the process to a compound having a higher carbon-tohydrogenratio. olen, substantially all hydrogen removed from the hydrocarbonadds to the iodine to form Hl. ln the presence of said oleiin at leastpart of the hydrogen adds to thev olefin, thus reducing the amount ofhydrogen that must' be accepted by iodine for a given total removal ofhydrogen from the charge. The present invention, therefore, reduces theiodine requirement of the process or, conversely, permits the productionof a greater amount of the desired product per unit weight of iodineemployed.

Thev process of the present invention has wide application in theconversion of various types of hydrocarbons to related hydrocarbonshaving at least one different carbon-to-carbon linkage and a highercarbon-to-hydrogen ratio. be dehydrogenated to alkenes, alkadienes andacetylenes. For example, isobutane can be dehydrogenated to isobutene,n-butane to butene-l, butene-2 and butadiene- 1,3 and n-pentane andisopentane to the corresponding pentenes and pentadienes. Varioushydrocarbons mayl be coupled through acyclic carbon atoms. For instance,propylene can be dehydrocoupled to give di-allyl and isobutylenedehydrocoupled to give di-methallyl.

quaternary carbon atoms, whether saturated or unsaturated, can becyclized, often with aromatization. For example, n-hexane .can bedehydroaromatized to benzene; n-heptane to toluene; n-octane to o-xyleneand ethylbenzene; 2,5-dimethylhexane to p-xylene; hexadiene-1,3 to`benzene; hexene-l to` cyclohexane; and the like. As dis-v closed andclaimed in copending U.S. application Serial No. 489,303 of I. H. Raleyand R. D. Mullineaux, filed February 18, 1955, acyclic hydrocarbonscontaining at least six carbon atoms, one of which is a quaternary car--bon atom, can be structurally isomerized and/ or dealkyl' ated tochangethe quaternary C-atom to a non-quaternary C-atom. For example,2,2,5-trimethylhexane can be demethylated and dehydroaromatized to givep-xylene and also dehydroisomerized with demethylation and aromatizationto give m-xylene. carbon atoms being acyclic, as in the precedingillustrapatented Mar. 31, 1959 In the absence of hydrogen accepting'Thus, alkanes of at least three carbon atoms can.-

Acyclic' hydrocarbons containing at least six contiguous non'- Insteadof all of. the* volved in the conversion and the formation of a newcarbon-to-carbon bond, as already indicated, can be in one or moreacyclic hydrocarbon radicals attached to a cyclic nucleus, such as anaromatic nucleus. In that case, one or more of the cyclic carbon atomsmay be involved in the conversion when it involves the formation of anew ring, such as an aromatic ring. For example, ethylbenzene can bedehydrogenated to styrene; toluene dehydrocoupled to dibenzyl andstilbene; o-diethylbenzene dehydroaromatized to naphthalene;ortho-methylpropylbenzene dehydroaromatized to naphthalene;o-methylethylbenzene dehydrogenated to o-methylstyrene; n-butylbenzenedehydrogenated to 4-phenylbutadiene-L3 and dehydroaromatized tonaphthalene; 2,3-diethylnaphthalene to anthracene; butylcyclohexane tonaphthalene; and butylcyclopentane to indene. Further, the reaction withiodine is suitably employed in the dehydrogenation of hydroaromaticcyclic hydrocarbons, e.g., the conversion of cyclohexane to cyclohexeneor benzene, of methylcyclohexane to toluene, and the like.

The use of a hydrogen accepting olefin, according to the presentinvention, is particularly useful for those re- Iactions having hightheoretical iodine requirements, e.g., the dehydrocyclization ofparaiins and the dehydrogenation of naphthenes to aromatics. Thus, toconvert one pound of normal hexane to benzene merely in the presence ofiodine theoretically requires 11.8 pounds of iodine. Under practicalconditions somewhat more iodine may be required. The price of iodinebeing Well in excess of one dollar per pound, it is seen that, even whencompletely efficient recovery of the resulting hydrogen iodide from theproducts, reconversion thereof to iodine and reuse of the iodine isaccomplished, an expensive inventory of iodine is required to apply theprocess on a commercial scale; or, in the alternative, to avoid a largeiodine inventory, a low conversion per pass must be used and largeamounts of unconverted feed hydrocarbon separated from the products andrecycled. By operating in accordance with the present invention, eachatom of iodine charged serves to remove more than one atom of hydrogenfrom the original hydrocarbon charge, thus substantially reducing theamount of free iodine which must be charged to obtain substantiallycomplete conversion of the charge hydrocarbon or, conversely, permittingincreased conversion per pass when charging a relatively smallproportion of iodine.

It is believed that in the present process the hydrogen does not passdirectly from the feed hydrocarbon to the hydrogen accepting olelin, butrather that hydrogen is abstracted from the feed hydrocarbon by aniodine atom to form HI, and HI interacts with the hydrogen acceptingolefin to produce the corresponding saturated hydrocarbon and elementaliodine. Therefore, it is possible to carry out the present process byadding the major amount of iodine to the reaction zone in the form ofHI, but at least a small amount of I2 is preferably present in theinitial reaction mixture. The present invention is not to be construedas limited by the abovedescribed reaction mechanism.

Although it is generally preferable to employ elemental iodine as theiodine species charged to the reaction zone with the hydrocarbon feed,the iodine may also be ernployed in the form of certain of itscompounds. Hydrogen iodide may suitably be employed, as well as iodinecompounds which liberate iodine under the reaction conditions. Suchcompounds are, for example, the alkyl iodides, including polyiodides,aralkyl iodides, and the like.

The suitability of any particular olen for use as hydrogen acceptor in areaction in accordance with the present invention is readily determinedas follows:

A compound A is to be converted by reaction in the presence of iodineinto a compound B having a higher carbon-to-hydrogen ratio, i.e., thereaction involves dehydrogenation; an olefin R is to be employed as hy-4 drogen acceptor, being converted in the reaction to a hydrogenatedcompound RH2. The reactions involved may be written as shown inEquations 1 and 2 below, where g) signifies that the component is in thegaseous state.

AF1 is the standard free energy change of the reaction of Equation 1 andAF2 the standard free energy change of the reaction of Equation 2. Thismay be expressed, for example, in kilogram calories per gram mole; formost common compounds this value is found in, or readily calculatedfrom, thermodynamic tables, e.g., the

tables published by the American Petroleum Institute.

(API), Research Project 44, entitled Selected Values of Properties ofHydrocarbons and Related Compounds, Petroleum Research Laboratory,Carnegie Institute of Technology, Pittsburgh, Pa., October 31, 1954. Ifthe algebraic sum of AF1 and AF2 is a negative number (i.e., m+n 0),then the olefin R is suitable as a hydrogen acceptor in the reaction.Since the free energy for a given reaction varies with the temperature,AF1 and AF2 must be taken at the desired reaction temperature. In caseswhere compound A in Equation 1 is a nonaro matic compound and compound Bis an aromatic one, the standard free energy change AE1 is a largenegative number at temperatures suitable for the present reaction. Formost commonly occurring olens, AF2 at the same temperature is arelatively small positive or negative number. Therefore, in reactionswhere an aromatic is produced, the algebraic sum of the standard freeenergies generally is negative regardless of the particular olefinemployed as hydrogen acceptor. In those cases where Reaction 1represents the conversion of a paraflin to an olefin or diolelin or theconversion of a monoolefin to a diolelin, AE1 will generally be arelatively small negative number and the choice of the olene R is,therefore, more limited. It will usually be an olefin having a lowernumber of carbon atoms than compound A and of no greater degree ofbranching than compound A.

To illustrate the above relationship and calculations, assume that it isdesired to determine whether or not ethylene is suitable as hydrogenacceptor in the conversion of propane to propylene by means of iodine ata temperature of 527 C. (800 K.). The equations are set up as follows:

To determine the standard free energy change of the Reaction 1, i.e.,AE1, the standard free energies of formation of the several compoundsare read from the appropriate API Project 44 tables as follows (takingthe values at 800 K.):

The AF of an equation is the algebraic sum of the AFf values of theproducts minus the algebraic sum of the .AFfo values of the reactants.Hence and AF1+AF2 4.21 Kcal.

Thus, the above-described condition is met, namely, the 'f sum of thestandard free energy changes is a negative value, and it is concludedthat ethylene is a suitable hydrogen acceptor in the conversion ofpropane to propylene. When charge compounds of greater numbers of carbonatoms are to be converted, a separate equation is written for eachcompound formed as product of the reaction, and the criterion of summingthe AF values is separately applied to each of these equations asEquation 1.

For convenience of terminology, the term hydrogen accepting olefin isemployed herein to designate an olefin suitable for accepting hydrogenin the conversion of a particular compound, as determined by theabove-stated criteria.

Ethylene is the preferred hydrogen accepting olenv for use in thepresent invention. Thermodynamically, it is the most suitable onebecause at any given temperature the free energy change of theconversion of ethylene to ethane is a lower positive or greater negativenumber than that for the corresponding conversion of any other oleiin.Ethylene has further considerable advantages for use in the presentinvention in that it and its hydrogenation product, ethane, are lesssubject to cracking than the olefins of higher molecular weight.Similarly, ethylene is less subject to` ready conversion by any otherreaction in the presence of iodine than higher molecular Weight olefinswhich may be converted into more highly unsaturated compounds byreaction with iodine under the reaction conditions normally employed.

Propylene is a suitable olefin for use in many reactions in accordancewith the present invention, particularly where compound B in Equation l,supra, is an aromatic hydrocarbon. The AF2 for propylene is about 4kilocalories `greater (i.e., more positive) than for ethylene, attemperatures in the range employed in the present invention. Next toethylene, propylene is preferably employed, but any other olefin, suchas butene-l, butene-2, isobutene, a normal or branched pentene, hexene,or higher olefin may be employed, always provided that it meets thecriterion set out supra.

The olefin employed as hydrogen acceptor need not be charged in pureform. Mixtures of olefins, e.g., a mixed ethylenepropylene stream, maybe employed. The olefin may also be charged in admixture withhydrocarbons which are relatively inert under reaction conditions, e.g.,ethylene may be charged in admixturc with methane and/r ethane. Sincethe effectiveness of the `olefin as hydrogen acceptor depends on theequilibrium between the olefin and the corresponding paraffin, thepresence of the corresponding paraffin in the feed will tend to sup-`press this reaction and such paraffin is therefore preferably held to arelatively low concentration in the olefin charge stream.

'I'he olefin employed as hydrogen acceptor in the present process may bederived from any convenient source. Thermal and catalytic cracking ofpetroleum hydrocarbons furnishes large amounts of olefins in mostpetroleum refineries. Ethylene may be recovered from cracked gases or itmay be produced and recovered by any of numerous known processes, e.g.,those discussed in Petroleum Refiner, vol. 20, No. 9, pp. 220-225(September 1951).

The olefin employed as hydrogen acceptor may desirably be regeneratedfrom the corresponding parafiin recovered from the total reactionproducts. For example, when ethylene is employed as the hydrogenaccepting olefin, a C2 stream comprising ethylene and ethane isrecovered by distillation or separation from the other reaction productsand this stream may then be charged to an ethane cracking zoneoperating, e.g., at temperatures in the range from 700 to 850 C.,preferably between 760 and 820 C., at pressures ranging fromsubatmospheric to about 50 p.s.i.`, and at contact times of less thanone second. A C2 stream comprising a high concentration of ethylene isseparated from heavier byproducts of the cracking reaction and may bedirectly charged back to the conversion step ofthe present invention, or

6 the ethylene may be further purified 'and concentrated prior to beingrecycled.

The conditions for carrying out the conversion step of this inventionmay be selected such that in the absence of the iodine there would beonly a relatively low rate and amount of dehydrogenation. The conditionsdepend on the particular compound to be converted, on the hydrocarbonwhich it is desired to obtain as principal product, and on the compoundselected as hydrogen accepting olefin.

In the conversion of hydrocarbons to corresponding olefns, diolens andaromatics by reaction with iodine, the temperature required is at least300 C., generally being at least about 350 C. and usually preferably inthe range between 400 and 600 C., although higher temperatures may beutilized, eg., up to 700 C. or higher where the molecular weight of thehydrocarbons in the system is relatively low, eg., up to C4. The highertemperatures are not objectionable so long as other undesirable changesare not effected. However, excessively high temperatures are notrequired in order to effect suitable dehydrogenation ordehydrocyclization in the presence of iodine and hydrogen acceptingolefin. In the case of less ther- Qmally .stable charge substances, suchas hydrocarbons having six or more carbon atoms per molecule, thetemperature is suitably adjusted in the range between 400 and 575 C. Thehigher temperatures, e.g., between 450 and 575 C. may be employed whenethylene is the hydrogen accepting olefin and somewhat lowertemperatures, e.g., between 400 and 550 C. when another olefin is thehydrogen acceptor. With feeds of lower molecular weight, e.g., C3through C5, the hydrogen accepting olefin employed will generally beethylene` land the preferred temperature range for these systems isbetween 500 and 600 C.

The process is suitably carried out at various pressures, fromsubatmospheric to superatmospheric pressures in Vapor phase. Althoughatmospheric pressure is suitable and is. advantageous in most cases,other considerations such as factors which are involved in theseparation and recovery of the hydrogen iodide and hydrocarbon productsfrom the reactor eiuent stream make a super-v atmospheric pressure moredesirable in some cases. Thus,` the pressure can be at any value atwhich the reactants are suiciently vaporized at .a temperature at whichthe hydrocarbon is substantially thermally stable. The pressure employedis preferably in the range between l and l0 atmospheres, absolute, butmay be as high as 30 atmospheres and even higher.

The residence time of the reactants at the selected reaction conditionsdepends upon the particular hydrocarbon reactant, the proportions ofiodine and hydro,- gen accepting olefin in the reaction mixture, thetemperature and pressure and the nature of the dehydrogenation product.In general, it should be at least about 0.01 second and usually at leastabout 0.1 second while usually it should not be over about l minute, butit may be :as much as 3 to 5 minutes. With most common reactants thedehydrogenation is very rapid so that a residence time from 0.1 to 10seconds suffices and is preferred.

The ratio of hydrogen accepting olefin to the hydrocarbon to beconverted in the present reaction, which may be designated as hydrogendonor, may be varied over a wide range. This ratio may be expressed intheoretical equivalents of the hydrogen accepting olefin; onetheoretical equivalent, commonly referred to, for convenience, as onetheory, is the number of molesy required to accept the hydrogenliberated in the conversion of one mole of the hydrogen donor. The ratioemployed may suitably vary from 0.1 to l0 theories of hydrogen acceptingolefin, and is preferably in ythe range between 1 and 5 theories. Inselecting the ratio of hydrogen accepting olefin to hydrogen donor it isgenerally pre.-

ferred `not to exceed a volume ratio of olefin to donor- 2,sso, 249

of about 20:1. For example, in the complete conversion of n-hexane tobenzene:

one theory of olefin is four moles per mole of hexane. In vapor phase,the volume ratio is the same as the mole ratio; hence a volume ratio of20:1 (the maximum referred to above) equals 20 moles of olefin per moleof hexane, or 20/4=5 theories of olefin.

T he amount of iodine employed may also, for convenience, be expressedin theories. The theory or theoretical equivalent of iodine iscalculated on the basis of iodine acting as hydrogen acceptor, i.e.,ignoring the hydrogen accepting olefin in the system. For example, toconvert one gram molecular Weight of n-hexane to benzene requires eightgram atomic Weights, or four gram molecular weights, of elemental iodine(12); one theory of iodine in that reaction is, therefore, four molesper mole of n-hexane. The number of theories of iodine species chargedin the present reaction is suitably in the range from 0.01 to 0.8, andpreferably from 0.1 to 0.6 theory. When less than one theory of hydrogenaccepting olefin is employed the amount of iodine species required is inthe higher part of the range; whereas, when the amount of hydrogenaccepting olefin is two or more theories the amount of the iodine may beselected in the lower part of the suitable range. The amount ofelemental iodine charged with the feed to the reaction zone should be atleast about 0.05 mole of iodine per mole of hydrocarbon to be converted.At the more severe reaction conditions, e.g., higher temperatures andlonger residence times and with the higher molecular weight hydrocarbonfeeds, the amount of iodine to be charged should be at least 0.1 to 0.2mole per mole of hydrocarbon. By maintaining such a minimum ratio,undesirable side reactions such as thermal cracking are substantiallycompletely avoided.

Advantage may be taken in the present invention of the catalyticdecomposition of hydrogen iodide to iodine and hydrogen within thereaction zone, as disclosed in detail in copending patent applicationSerial No. 563,660, of the present applicants, tiled on February 6,1956. Suitable catalysts are the noble metals, e.g., platinum orrhodium, either unsupported or on a suitable porous support, such assilica gel. By virtue of such decomposition the amount of iodinerequired to be charged is reduced and may be within the lower part ofthe ranges stated above.

The present invention will be illustrated by means of the drawing, whichshows a schematic ow scheme of one method of operating the process. Forthe sake of illustration, n-hexane is assumed to be the chargehydrocarbon, to be converted into benzene by reaction with iodine in thepresence of ethylene as hydrogen accepting olefin. Hexane is chargedthrough line 11, from a source not shown. Ethylene is added to line 11by opening valve 12 in line 14 or valve 15 in line 52, the formersupplying ethylene from an outside source, not shown, and the lattersupplying it from a source described below. Two theories of ethylene aresuitably added in this manner, i.e., 8 moles of ethylene per mole ofhexane. Active iodine species is added to line 11 through line 16. Thismay include elemental iodine added through line 31 from a sourcedescribed below, HI or elemental iodine added through line 34 fromanother source described below and makeup elemental iodine, HI, or alkyliodide added to line 16 by opening valve 18. The mixture of hexane,ethylene and iodine species in line 11 may be vaporized and preheated byseparate equipment, not shown, and is then introduced into reaction zoneA, which may be a heated vessel or coil, in which the mixture ismaintained at a temperature in the range between 500 and 550 C. for from2 to 10 seconds. The reactor eiliuent is withdrawn through line 19 andthen passed to fractionator'B, which may be a conventional packed columnor bubble plate distillation column with the conventional associatedequipment including a reboiler and reflux condenser. Prior to enteringdistillation column B, the mixture may be cooled somewhat by indirectheat exchange in a heat exchanger, not shown, in line 19. Infractionator B the reactor eluent is separated to withdraw as overhead,through line 20, a stream comprising essentially ethane and ethylene, asdistillate, through line 21 a stream comprising essentially hydrogeniodine, and as bottoms through line 22 the total liquid hydrocarbonsincluding hexane, benzene produced in the reaction and other hydrocarbonproducts which may have been produced to a small extent, includinghexene. The liquid hydrocarbon bottoms also may contain elemental iodinepresent in the effluent in line 19. If the stream in line 22 containssubstantially no iodine, valve 24 in bypass line 25 is opened and thetotal hydrocarbon withdrawn through line 26 for further work-up,including separation of unconverted hexane from the reaction p roducts.The hexane may be recycled to line 11. If the stream in line 22 containselemental iodine it is passed to line 28 by closing valve 24 and openingvalve 29 and is introduced by line 28 into iodine separator C in whichthe iodine is separated from the hydrocarbon stream by suitable means,e.g., by fractional distillation. Hydrocarbon is then returned to line26 via line 30. The iodine recovered in the separator is returned to theprocess via lines 31 and 16.

The hydrogen iodide in line 21 may be returned for use in the process inthe form of hydrogen iodide by lines 21, 32, 34 and 16 on opening valve33, or the hydrogen iodide may be passed to HI converter D by closingvalve 33 and opening valve 3S in line 36. In HI converter D, elementaliodine is recovered from the HI by suitable means, e.g., by oxidation ofthe HI with chlorine to regenerate elemental iodine, which is thenreturned to the process via lines 38, 34 and 16.

The C2 stream in line 20 may be discarded from the system by openingvalve 39 in line 40 or it may be returned for reuse by opening valve 41in line 42 to pass the ethane through line 44 into cracking zone E whichis operated at a temperature of approximately 820 C. with a very shortcontact time to produce a mixture of ethane and ethylene. Eluent fromcracking zone E has its temperature rapidly reduced by direct heatexchange with a suitable quench, such as Water, introduced via line 46and is then passed through line 45 into phase separator F where anaqueous layer is separated and withdrawn via line 48 and the hydrocarbonvia line 49. From line 49 the hydrocarbon stream is passed to separatorG which may represent fractional distillation, adsorption or absorptionequipment in which lighter material than ethylene is removed by line 50,heavier material by line 51 and an ethylene stream by line 52 for returnto line 11. The ethylene may be highly puried in separator G, but asubstantial amount of ethane may be retained in it without seriouslyaffecting the effectiveness of the ethylene as hydrogen acceptingolefin.

In the drawing and description of the process, much necessary auxiliaryequipment such as valves, pumps,l

heat exchangers, and the like has not been shown in order to simplifypresentation of the process. The location of such equipment will beapparent to those skilled in the art.

The description of the process given above in connection with thedrawing is for illustrative purposes only and not to be considered alimitation on the process of the present invention. Different methods ofrecovering the reactor effluent and separating hydrogen iodide, iodineand reaction products therefrom may be employed.

The invention will be further illustrated by means of the followingexample: Two runs were made in which normal butane, diluted with a smallamount of helium, was charged to a reaction zone in the presence ofelemental iodine and ethylene. The reaction conditions for the runs,designated runs 1 and 2, and the essential results obtained arepresented in Table I.

Table I Run No 1 A 2 B Temperature, C 550 550 600 600 Pressure, mm. Hg950 760 1, 000 760 Residence time, seconds- 2. 2 2. 2 2 2 DlluentMole/mole feed (C4). He 0.063 He 0.066 Iz/CiHiu Mole ratio 0. 215 0.2150.36 0.36 Theories of Iza- 0. 215 0.215 0.36 0. 36 C2H4/C4Hiu Mole ra 0.48 0. 0 0. 53 0. 0 Theories ol CgHib 0.48 0.0 53 0. 0

Conversion of 04H10, Percent mole to:

04H8 16 0 19.0 43.8 34.0 04H5 0.9 0. 2 4. 7 1. 2 (J1-C3 (C4equvalents)--- 2. 3 0. 0 7. 3 0. 0 Coke 0.0 0.0 0 0l 0.0 Loss 3.2 0. 05. 1 0. 0

Total 22.4 19.2 60.91 35 2 selectivity, percent mole 75-88 100 80-87 100Conversion of 02H4 to CzHs,

percent -9 3 between and 40 Conversion of I2, percent,... 100 99 Run No.1 was carried out at 550 C. with an iodineto-butane mole ratio of 0.215and an ethylene-to-butanc mole ratio of 0.48. Run No. 2 was made at 600C. with an iodine-to-butane mole ratio of 0.36 and ethyleneto-butaneratio of 0.53. Residence time was approximately two seconds in each run.The ratios of iodine and of ethylene-to-butane, expressed as theories,are based on the stoichiometric requirement for conversion of the butaneto butylene, and are, therefore, numerically equal to the respectivemole ratios. For purposes of comparison, Table l also shows runs A and Bwhich represent the calculated maximum conversion obtainable in theabsence of hydrogen accepting olefin at the reacting conditions of runsl and 2, respectively, as determined by thermodynamic equilibrium,assuming an inert diluent to be present in an amount equal to theethylene employed in runs 1 and 2, respectively. In numerous actualexperiments carried out in the absence of hydrogen accepting olefin, ithas been found that the conversion actually obtained is on the order of80% of thermodynamic equilibrium conversion at the condition of theseruns.

The eectiveness of ethylene as hydrogen accepting olen is indicated bythe results shown for conversion of C4H10 l[o Gill-I8 and CH6 III funN0. 1, Of butyl' enes was recovered compared to the theoretical maximumof 19.0% and compared to the normally obtainable 16%. Additionalbutylene produced is included in the 3.2% loss. Butadiene yield wasincreased to 0.9% from the theoretical maximum 0.2%. Under the somewhatmore severe conditions of run No. 2, the normal butylenes yieldsubstantially exceeded the yield theoretically possible with the amountof iodine charged in the absence of hydrogen accepting olefins; theactual yield was 43.8%, compared with a theoretical of 34.0%. Similarly,the butadiene yield exceeded very substantially the theoretical, being4.7% compared with a theoretical, 1.2%, or nearly 400% of thetheoretical butadiene yield.

The use of the small amount of helium diluent in these runs is forreasons not connected with the use of ethyleue. Substantially identicalresults are obtained, in suitable equipment, when the helium diluent isomitted.

We claim as our invention:

1. A process for converting a first hydrocarbon containing at leastthree carbon atoms per moluecule and containing non-aromaticcarbon-to-hydrogen bonds into at least a second hydrocarbon having ahigher carbonto-hydrogen ratio which comprises subjecting a vapormixture comprising said first hydrocarbon, a hydrogen accepting olefinhaving a lower carbon number than said iirst hydrocarbon and a reactantiodine species in suicient amount to `furnish at least 0.05 mole ofiodine per mole of said first hydrocarbon to a temperature of at least300 C. to effect a C-to-H bond cleavage in said iirst hydrocarbon andconversion of at least part of said oletin to the correspondingparaiiin, and recovering said second hydrocarbon.

2. A process according to claim l in which said first hydrocarbon is analiphatic compound and said second hydrocarbon is an aliphatic compoundhaving at least one more oleiinic double bond.

3. A process according to claim 1 in which said first hydrocarbon isaliphatic and said second hydrocarbon is aromatic.

4. A process according to claim 1 in which said hydrogen acceptingolefin is ethylene.

5. A process for converting a lirst hydrocarbon containing at leastthree carbon atoms per molecule and containing non-aromaticcarbon-to-hydrogen bonds into at least a second hydrocarbon having ahigher carbon-tohydrogen ratio which comprises contacting a vapormixture comprising said rst hydrocarbon, at least 0.1 theory of ahydrogen accepting olefin having a lower carbon number than said firsthydrocarbon and no less than 0.05 mole per mole of said trst hydrocarbonbut no more than 0.8 theory of elemental iodine at an elevatedtemperature in the range between 300 and 600 C. to effect a C-to-H bondcleavage in the molecule of said first hydrocarbon and conversion of atleast part of said olen to the corresponding paraffin, and recoveringsaid second hydrocarbon.

6. A process according to claim 5 in which the temperature is in therange between 400 and 575 C., the contact time in the range between 0.1and 10 seconds, the proportion of iodine in the range between 0.1 and0.6 theory, and the proportion of said hydrogen accepting olefin in therange between 1 and 5 theories.

7. A process for converting normal butane into butylenes and butadienewhich comprises contacting a mixture comprising butane, ethylene and atleast 0.05 mole of iodine per mole normal butane at a temperature in therange between about 500 and 600 C. for a time in the range between 0.1and 10 seconds and recovering from the reaction product at leastbutylenes and butadiene.

8. A process for converting acyclic hydrocarbons containing at least sixcontiguous nonquaternary carbon atoms to aromatics which comprisescontacting a mixture of at least one of said hydrocarbons, ethylene andat least 0.2 mole of iodine per mole of acyclic hydrocarbon at atemperature in the range between 300 and 575 C. for a time in the rangebetween 0.1 and 10 seconds whereby said acyclic hydrocarbons areconverted to aromatic hydrocarbons and said ethylene to ethane.

9. A process for converting hydroaromatic cyclic hydrocarbons intoaromatics which comprises contacting a mixture of at least one of saidhydrocarbons, ethylene and at least 0.2 mole of iodine per mole ofhydroaromatic cyclic hydrocarbon at a temperature in the range between300 and 575 C. for a time in the range between 0.1 and 10 secondswhereby said hydroaromatic hydrocarbons are converted to aromatichydrocarbons and ethylene to ethane.

References Cited in the tile of this patent UNITED STATES PATENTS1,925,421 Van Peski Sept. 5, 1933 2,259,195 Baehr et al. Oct. 14, 19412,392,739 Horeczy et al. Jan. 8, 1946 2,415,537 Schulze et al Feb. 11,1947 FOREIGN PATENTS 849,804 France Aug. 28, 1939

1. A PROCESS FOR CONVERTING A FIRST HYDROCARBON CONTAINING AT LEASTTHREE CARBON ATOMS PER MOLUECULE AND CONTAINING NON-AROMATICCARBON-TO-HYDROGEN BONDS INTO AT LEAST A SECOND HYDROCARBON HAVINGS AHIGHER CARBONTO-HYDROGEN RATIO WHICH COMPRISES SUBJECTING A VAPORMIXTURE COMPRISING SAID FIRST HYDROCARBON, A HYDROGEN ACCEPTING OLEFINHAVING A LOWER CARBON NUMBER THAN SAID FIRST HYDROCARBON AND A REACTANTIODINE SPECIES IN SUFFICIENT AMOUNT TO FURNISH AT LEAST 0.05 MOLE OFIODINE PER MOLE OF SAID FIRS: HYDROCARBON TO A TEMPERATURE OF AT LEAST300*C. TO EFFECT A C-TO-H BOND CLEAVAGE IN SAID FIRST HYDROCARBON ANDCONVERSION OF AT LEAST PART OF SAID OLEFIN TO THE CORRESPONDINGPARAFFIN, AND RECOVERING SAID SECOND HYDROCARBON.